Cross-linked polyurethanes based on aromatic/aliphatic copolyesters

ABSTRACT

A CROSS-LINKING POLYESTER-URETHANE PRODUCED BY (A) ADMIXING AT LEAST ONE LINEAR COPOLYESTER, SUCH COPOLYESTER (I) PRODUCED BY THE REACTION OF ONE OR MORE DIOLS OR POLYETHER GLYCOLS WITH AT LEAST TWO DIFFERENT DICARBOXYLIC ACIDS, ANHYDRIDES OF DICARBOXYLIC ACIDS, ABOUT 40OR METHYL ESTERS OF DICARBOXYLIC ACIDS, ANHY80 MOLE PERCENT OF SAID CARBOXYLIC ACIDS, ANHYCARBOXYLIC ACIDS BEING AROMATIC AND ABOUT 60-20 MOLE PERCENT OF SAID DICARBLXYLIC ACIDS, ANHYDRIDES OF DICARBOXYLIC ACIDS OR METHYL ESTERS OF DICARBOXYLIC ACIDS BEING ALIPHATIC, (2) HAVING A HYDROXYL NUMBER OF ABOUT 20-225 (3) HAVING A MOLECULAR WEIGHT OF ABOUT 500 TO ABOUT 10,000, (4) HAVING ABOUT TWO HYDROXYL GROUPS PER MOLECULE WITH (B) AT LEAST ONE ORGANIC DIISOCYANATE, THE MOLAR RATIO OF ISOCYANATE CONTAINED ON THE DIISOCYANATE TO HYDROXYL CONTAINED ON THE COPOLYESTER BEING SUFFICIENT FOR THE CONDITIONS OF THE REACTION TEMPERATURE AND REACTION TIME TO FORM A POLYESTER-URETHANE HAVING ABOUT TWO HYDROXYL GROUPS PER MOLECULE, AND (C) ADMIXING THE POLYESTER-URETHANE WITH AT LEAST ONE CROSS-LINKER HAVING A FUNCTIONALITY GREATER THAN 2, THE MOLAR RATIO OF GROUPS CONTAINED ON THE CROSS-LINKER TO HYDROXYL CONTAINED ON THE POLYESTER-URETHANE BEINFG ABOUT 1.0/1.0 TO 4.0/1.0 AT A TEMPERATURE AND FOR A TIME SUFFICIENT TO PRODUCE THE CROSS-LINKED POLYESTER-URETHANE.

United States Patent US. Cl. 260-75 NK 29 Claims ABSTRACT OF THEDISCLOSURE A cross-linking polyester-urethane produced by (A) admixingat least one linear copolyester, such copolyester (1) produced by thereaction of one or more diols or polyether glycols with at least twodilferent dicarboxylic acids, anhydrides of dicarboxylic acids, ormethyl esters of dicarboxylic acids, about 40- 80 mole percent of saiddicarboxylic acids, anhydrides of dicarboxylic acids or methyl esters ofdicarboxylic acids being aromatic and about 60-20 mole percent of saiddicarboxylic acids, anhydrides of dicarboxylic acids or methyl esters ofdicarboxylic acids being aliphatic, (2) having a hydroxyl number ofabout 20-225, (3) having a molecular weight of about 500 to about10,000, (4) having about two hydroxyl groups per molecule with (B) atleast one organic diisocyanate, the molar ratio of isocyanate containedon the diisocyanate to hydroxyl contained on the copolyester beingsufficient for the conditions of the reaction temperature and reactiontime to form a polyester-urethane having about two hydroxyl groups permolecule, and (C) admixing the polyester-urethane with at least onecross-linker having a functionality greater than 2, the molar ratio ofgroups contained on the cross-linker to hydroxyl contained on thepolyester-urethane being about 1.0/1.0 to 4.0/ 1.0

at a temperature and for a time sufficient to produce the cross-linkedpolyester-urethane.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of United States application, Ser. No. 102,919,filed Dec. 30, 1970 and now abandoned.

BACKGROUND OF THE INVENTION This invention relates topolyester-urethanes that are useful as adhesives, coating compositions,primers, for binding magnetic and/ or conductive particles to a suitablesupport to thereby produce magnetic recording media, and the like.

SUMMARY OF THE INVENTION A cross-linked polyester-urethane produced by(A) admixing at least one linear copolyester, such copolyester (1)produced by the reaction of one or more diols or polyether glycols withat least two diiferent dicarboxylic acids, anhydrides of dicarboxylicacids, or methyl esters of dicarboxylic acids 3,804,810 Patented Apr.16, 1974 ice (2) having a hydroxyl number of about 20-225 (3) having amolecular weight of about 500 to about 10,000 (4) having about twohydroxyl groups per molecule with at a temperature and for a timesufiicient to produce the cross-linked polyester-urethane.

There is also provided by this invention a process for adheringmaterials with the above cross-linked polyesterurethane, compositionscontaining the cross-linked polyester-urethanes, magnetic recordingmedia made with the cross-linked polyester urethanes and other aspectsof the invention which will be described later.

These cross-linked polyester-urethanes when used as adhesives, provideexcellent adhesion to any suitable material and especially to flexiblefilms. As well as this, such cross-linked polyester-urethanes can beused to make coating compositions, primers, and for binding magneticand/or conductive particles to a suitable support to thereby producemagnetic recording media.

DESCRIPTION OF THE INVENTION The copolyesters The copolyesters areproduced by (1) an esterification reaction, i.e. the reaction of one ormore diols or polyether glycols with at least two dilferent dicarboxylicacids or two difierent anhydrides of dicarboxylic acids or (2) by atransesterification reaction, i.e. the reaction of one or more diols orpolyether glycols with at least two different esters of dicarboxylicacids.

The copolyesters are produced by conventional techniques which are wellknown. Ordinarily, the reactants will be admixed in a suitable reactionvessel, with heating to a temperature of about C.-250 C., for /2-8hours, to produce the polyester.

The diols can be aliphatic or aromatic. The hydrocarbon radicals in thediols can contain, be substituted with or interrupted withnon-interfering groups such as N, O, S, halogen and the like. Suitablediols include:

ethylene glycol propylene-1,2-glycol propylene-l,3-glycolbutylene-1,3-diol butylene-1,4-diol butylene-2,3-diol neopentylglycoli.e. 2,2-dimethylpropane-1,3-diol 2,2-diethylpropane-1,3-diol2-methyl-2-propylpropane-1,3-diol decamethylene glycol dodecamethyleneglycol thioethylene glycol N-methyl diethanolamine monoethyl ether ofglycerine alpha and beta-allyl ethers of glycerol,

and the like.

Preferably the diols will have about 2-8 carbon atoms;

most preferably they will have about 2-6 carbon atoms.

A preferred diol is ethylene glycol.

If desired, one or more polyether glycols can be used with the diols.Suitable polyether glycols include polytetramethylene ether glycol,polyethylene glycol, polypropylene glycol, diethylene glycol and thelike. Such polyether glycols can have a molecuar weight of aboutZOO-10,000, preferaby about SOD-4,000 and most preferably about 1,000. Apreferred polyether glycol is polytetramethylene ether glycol.

The dicarboxylic acids can be aliphatic, cycloaliphatic, unsaturated oraromatic. The hydrocarbon radicals in the dicarboxylic acids cancontain, be substituted with, or be interrupted by non-interferinggroups such as O, S, N, halogen, keto and the like. Suitabledicarboxylic acids include: malonic, succinic, gluatric, adipic,pirnelic, suberic, azelaic, sebacic, brassylic, maleic, fumaric,dilinoleic, diphenic, phthalic, tetrachlorophthalic, isophthalic,terephthalic, orthophthalic acid, cyclohexane dicarboxylic acidp-phenylene diacetic, naphthalene dicarboxylic acid, dihydromuconicacid, beta-methyl adipic acid, trimethyl adipic acid,ethylether-2,2'-dicarboxylic acid, and the like.

If desired, one can use anhydrides of the above dicarboxylic acids suchas phthalic anhydride, tetrahydrophthalic anhydride or the like. Apreferred dianhydride is phthalic anhydride.

Preferred dicarboxylic acids include terephthalic acid, isophthalicacid, orthophthalic acid, azelaic acid, adipic acid, and a mixture of C-C aliphatic dicarboxylic acids.

Preferably, the dicarboxylic acids or anhydrides of dicarboxylic acidswill have about 4-12 carbon atoms.

Preferably, on a 100 mole percent acid basis, about 40 to about 80 molepercent should be aromatic acid and about 20 to about 60 mole percentshould be aliphatic acid. When one or more aromatic acid is used inconjunction with one or more aliphatic acid, preferred acid mixturescontain -65 mole percent terephthalic acid, 0-40 mole percentisophthalic acid, 0-60 mole percent orthophthalic acid or phthalicanhydride, 0-60 mole percent adipic acid, O-60 mole percent azelaic acidand 0-60 mole percent mixed aliphatic C -C acid, such acids beingpresent in an amount so that the total amount of aromatic acid is about40 to about 80 mole percent and the total amount of aliphatic acid isabout 20 to about 60 mole percent.

The following are especially preferred acid mixtures; such acid mixtureshave the mole percent limitations described in the immediately precedingparagraph.

Mole percent 1 Designation Most oiacid Especially especially mixtureAcid or anhydride preferred preferred A Terephthalic acid 28-38 33Isophthalic acid..- 12-22 17 azelaic acid 40-60 50 B Orthophthalic acidor phthalic 40-60 50 anhydride. Adipic acid 40-60 50 C Tcrephthalic acid45-65 55 Azelaic acid 33-55 45 D Terephthalic acid. 35-45 40 Isophthalicacid.. 50 Azelaic acid 5-15 10 Adipic acid 5-15 10 E Terephthalic acid45-55 50 isophthalic acid -25 Azelaie acid 20-40 30 F orthophthalic acidor phthalic 40-60 50 anhydride. Mixture of C4-C0 aliphatic (11- 40-60 60carboxylic acids.

G Terephthalic acid. 5-15 10 orthophthalic acid or phthalic 40-60 50anhydride. Adipic acid -55 40 l 100 mole percent acid basis.

In the making of the copolyester, at least two different (a)dicarboxylic acids, (b) anhydrides of dicarboxylic acids, or (c) estersof dicarboxylic acids will be reacted with one or more diols ofpolyether glycols. Thus, the copolyesters of this invention are to bedistinguished from a polyester formed from one dicarboxylic acid,anhydride or dicarboxylic acid or methyl ester of a dicarboxylic acidwith one or more diols or polyether glycols.

The copolyester should have about two hydroxyl groups per molecule, thatis should be hydroxyl terminated, and should have a hydroxyl number ofabout 20- 225, preferably 40-225, and most preferably about 40- 60.

Ordinarily, the copolyester will have a molecular weight of about 500 toabout 10,000, preferably about 1,500-4,000 and most preferably about1,500-3,000.

The diisocyantes The diisocyantes for use in this invention can bealiphatic or aromatic. Suitable isocyanates include:

hexane-1,6-diisocyanate decane-1,10-diisocyanate diisocyanates derivedfrom dimerized fatty acids phenylene-1,4-diisocyanatetoluene-2,4-diisocyanate toluene-2,6-diisocyanatenaphthylene-l,S-diisocyanate diphenylmethane-4,4-diisocyanatediphenylmethane-3,3'-dimethoxy-4,4-diisocyanatedicyclohexylmethane-4,4'-diisocyanate, etc.

Perefered is toluene-2,4-diisocyanate, toluene-2,6-disocyanate ormixtures thereof.

The cross-linkers The cross-linkers can be organic compounds thatcontain groups that are reactive with the hydroxyl groups contained onthe polyester-urethane.

The cross-linkers have an average functionality 1 greater than 2. At thepresent time no reason is seen to use a cross-linker having an averagefunctionality greater than about 8. Often the cross-linker will have anaverage functionality of about 3-6; preferably it will have an averagefunctionality of about 4-6 and more preferably about 4-5 and mostpreferably about 4.

One form of suitable cross-linkers are aliphatic or aromaticpolyisocyanates including:

4,4, "-triisocyanato triphenyl methane 1,3,5-triisocyanato benzene2,4,6-triisocyanato toluene, and the like biurets of any of thepreviously described diisocyanates such as the trimerization product ofhexane-1,6-diisocyanate of the formula:

CON-(CH1) s-N-C O-NH-(CHzh-NC O O NH-(CHzh-NC Otoluyl-2,4,6-triisocyanate naphthalene-1,3,7-triisocyanatediphenylmethane-2,4,4-triisocyanate triphenylmethane triisocyanateadduct of one or more diisocyanates (such as any of the previouslydescribed diisocyanates) with one or more polyol containing about 3 toabout 6 hydroxyl groups (such as propane triol, 1,2,6-hexane triol,trimethyolpropane, pentaerythritol, sorbitol and the like) to obtain across-linker having a functionality of greater than 2 but no greaterthan about 8.

A preferred polyisocyanate is the adduct of aromatic diisocyanates (suchas any of the previously described di- Functionality is the number ofgroups (such groups being reactive with hydroxyl groups on thepolyester-urethane) per molecule of cross-linker.

isocyanates) with trimethylolpropane in a :2 mole ratio to yield apolyisocyanate having a functionality'of 4, such as the adduct oftoluene-2,4-diisocyanate, toluene-2,6-diisocyanate or mixtures thereofwith trimethylolpropane in a 5:2 mole ratio.

Amino or nitrogen containing resins such as melamineformaldehyde resins,urea-formaldehyde resins or benzoguanamine formaldehyde resin areanother form of crosslinker. If such resins are used however, to obtainsufficient cross-linking, it may be necessary to apply heat.

If unsaturated copolyester is used (i.e. one produced with at least someunsaturated acids or unsaturated acid anhydride) to produce thepolyester-urethane, then such unsaturated polyester-urethane can becross-linked by admixing it with a suitable free radical polymerizationcatalyst such as benzoyl peroxide. Of course, a free radicalpolymerization catalyst cross-linker will not have the functionality thepreviously described cross-linkers have.

The solvents It is often desirable to have the reaction between the (1)copolyester and the diisocyanate and (2) the polyester-urethane and thecross-linker take place in the presence of an inert organic solvent.Suitable solvents include aromatic hydrocarbons such as toluene, xylene,tetrahydronaphthalene, decahydronaphthalene, etc.; chlorinatedhydrocarbons such as methylene chloride, chloroform, dichloroethane,trichloroethane', ethers such as diisopropyl ether, tetrahydrofuran,dioxane, ethylene glycol dimethyl ether, etc.; esters such as ethylacetate, butyl acetate, etc.; ketones such as acetone, methyl ethylketone, methyl isobutyl ketone, cyclohexanone, etc.

The process The polyester-urethane is prepared by admixing polyester anddiisocyanate, and if desired organic liquid solvent, in a suitablereaction vessel at a temperature and for a time suilicient for thepolyester-urethane to be formed. If desired a catalyst may be used suchas trimethylpyridine, N-ethyl morpholine, diazabicyclo-(2,2,2)- octaneor organic metal compounds (for example dibutyl tin dilaurate).

The reaction time required to produce the polyesterurethane can varysomewhat depending upon the reactivity of the diisocyanate used andwhether or not a catalyst is used. Generally, however, the reaction timewill be between about A and 8 hours. The reaction temperature can bebetween about 4' C. and 180 C.

The molar ratio of isocyanate (contained on the diisocyanate) tohydroxyl (contained on the copolyester) is sufficient for the conditionsof the reaction temperature and reaction time to form a polyesterurethane having about two hydroxyl groups per molecule, that is, beinghydroxyl terminated. Ordinarily, the molar ratio of isocyanate(contained on the diisocyanate) to hydroxyl (contained on the polyester)should be about 0.7/ 1.0 to about 1.0/1.0, preferably about 0.7/1.0 toabout 0.98/1.0, more preferably about 0.75/1.0 to about 0.90/1.0 andmost preferably about 0.80/1.0 to 0.85/1.0. Because of the abovedescribed ratio of isocyanate to hydroxyl, the polyester-urethane willcontain little or no free NCO groups. Although theoretically apolyesterurethane having hydroxyl termination would not be produced whenthe molar ratio of isocyanate (contained on the diisocyanate) tohydroxyl (contained on the polyester) is 1.0/1.0, it has been found thatunder the reaction conditions above-described, a hydroxyl terminatedpolyester-urethane is formed.

Preferably, the polyester-urethane will have a hydroxyl number of about4.0 to about 22.5, and more preferably about 816.

Preferably, the polyester-urethane will have a molecular weight of about5,000 to about 28,000 and more preferably about 7,000 to about 14,000.

Just before use the polyester-urethane is admixed with the cross-linker.The molar ratio of groups (contained on the cross-linker) to hydroxyls(contained on the polyester-urethane) should be about 1.0/1.0 to about4.0/1.0, preferably about 1.5/1.0 to about 2.5/1.0. The admixture cancontain about 0.5% to about 60%, preferably about 20% to about 60% byweight polyester-urethane which can be obtained by the evaporation ofsolvent or addition of solvent.

Cross-linking will take place at room temperature in about /2 hour to 5days depending on the cross-linker used. To hasten cross-linking and toinsure a good bond between the materials being adhered, heat and/orpressure can be applied.

Utility; compositions The cross-linked polyester-urethanes of thisinvention can be used as adhesives, coating compositions, primers andfor binding magnetic and/or conductive particles to a suitable supportto thereby produce magnetic recording media and the like.

Any suitable materials can be adhered with the crosslinkedpolyester-urethanes of this invention including paper, cellulose,polyester including polyterephthalate, polypropylene, polyethylene,polyvinyl chloride copolymers of vinylidene chloride and vinyl chloride,vinyl acetate and copolymers of vinyl acetate with other free radicalpolymerizable monomers, polyamides, flexible films, including those madefrom any of the foregoing that are suitable for making flexible films,metal foils, rubber and the like. Of course, the same materials ordifferent materials can be adhered to each other.

Ordinarily, the process for adhering materials will comprise:

(l) applying the admixture of the cross-linker and polyester-urethane tothe surface of material, and

(2) placing another material in contact with the admixture that has beenapplied to the material described in (1).

If desired, a third step in the above process can be the application ofheat, pressure or heat and pressure.

The admixture of polyester-urethane and cross-linker can be applied tomaterials from a solution containing about 05-60%, preferably about 20%to about 60% by weight cross-linker and polyester-urethane. If desired,the solution of the polyester-urethane in its reaction media canbeadmixed with the cross-linker, and the resulting admixture useddirectly, preferably after adjusting the percent solids, if necessary,by the evaporation of existing solvent or addition of more solvent.After the resulting solution is applied to material, the solvent is thenremoved.

If the admixture of cross-linker and polyester-urethane is to be used asan adhesive, adjuncts such as inert high molecular weight compounds suchas polyvinyl chloride, polyvinyl acetate and the like can be added tothe adhesive solutions.

If the admixture of cross-linkers and polyesterurethanes is to be usedas coating compositions, adjuncts such as pigments, fillers,plasticizers and the like can be added to them. Examples of suitablepigment include titanium dioxide, iron oxide, lead chromate, chromiumoxide, phthalocyanines, carbon black, zinc oxide, magnesium oxide,antimony oxide, lithopone, zinc chromate, red lead, aluminum (powder orflake), zinc stearate, aluminum stearate, glass microbubbles, aluminumsilicate, magnesium silicate, calcium sulfate, barium sulfate, silicondioxide, potassium aluminum silicate, calcium carbonate, magnesiumsilicate, calcium silicate, amorphous silica, mica, bentonite, asbestos,particles of polymer that has a high enough glass transition point sothat they do not significantly coalesce at the prevalent dryingconditions.

Pigment can be present in an amount at or up to the critical pigmentvolume (that level of pigmentation in a dry paint film where justsufiicient binder is present to fill the voids between the pigmentparticles). Often pigment will be present in an amount of about 0.5% toabout 60% by volume (based on combined volume of the pigment and thefilm-forming polymer).

The cross-linked polyester-urethanes can be used as binders for magneticrecording media. For this utility the polyester-urethanes can be blendedwith certain pigments such as magnetic and/or conductive particles,solvent (such as those previously enumerated), crosslinker and ifdesired particle dispersant. Any suitable mixing means can be used suchas sand-grinding, ball milling, high speed mixing and the like.

Suitable magnetic particles include magnetic iron oixde, chromiumdioxide, ferritic materials having the composition MeFe Q, where Me is adivalent transitional metal ion, such as Mn++, Fe++, Ni++, Co++, Cu++,Zn++, Cd+ or Mg++ or mixtures thereof.

Suitable non-magnetic conductive particles include carbon particles, andmore particularly carbon black, graphite or mixtures thereof. Othernon-magnetic conductive particles can be used also.

Ordinarily, the magnetic particles and/or non-magnetic conductive carbonparticles will be present in an amount of about 65-80%, preferably20-70% by weight, based on the total weight of the polyester-urethane.

Suitable particle dispersants include organic materials of theamphoteric types, such as soya lectithin and organic materials that canbe anionic, cationic or nonionic, such as polymers of about 12-18 carbonatoms containing -OH or -COH functionality (for example, stearic acid),sodium lauryl sulfate and dioctyl sodium sulfosuccinate. Preferredparticle dispersants are the polyesters bearing polyethyleneimineterminal groups described in US. patent application, Ser. No. 776,774,filed Nov. 18, 1968, in the name of D. R. Thompson, and now abandoned,and the continuation-in-part thereof having Ser. No. 120,773, filed Mar.3, 1971, which is still pending the disclosures of which are herebyincorporated by reference. The polyesters bearing polyethyleneimineterminal groups are represented by the structure:

where R R and R, can be hydrogen, alkyl radicals of 1 through 4 carbonatoms, -CH CH NH or CH CH OH; R, can be hydrogen or an alkyl radical of1 through 4 carbon atoms; Z can be an organic linking radical;

X can be an alkylene radical of-2 through 18 carbon atoms or phenylene;

Y can be an alkylene radical of 2 through 18 carbon atoms;

D can be phenyl or a straight or branched chain alkyl radical of 1through 18 carbon atoms; and n is a number 10 through 500; a is a number1 through 2000; and b is 0 or 1;

the n/a quotient being greater than 1.

Preferred are those of Formula 1 where D is a straight or branched chainalkyl radical of 3 through 12 carbon atoms, n is a number 20 through200, a is number 3 through 500 and b is 1. Especially preferred is thathaving the structure:

PREPARATION OF THE ANTI-FLOCCULATING AGENTS segment, is derived from apolyethylenimine.

The precursors of these segments are separately prepared and then linkedtogether by reacting them under appropriate conditions.

(A) Preparation of the polyester This precursor can be prepared by anyof the wellknown polyester-forming reactions. Illustrative of these are(1) Polymerization of lactones such as propiolactone, caprolactone andpivalolactone.

(2) Condensation of hydroxy acids such as emu-hydroxypropionic acid,a,w-hydroxydecanoic acid and 12- hydroxystearic acid.

(3) Condensation of glycol and dicarboxylic acid systems such asethylene glycol/decamethylene dicarboxylic acid, hexamethyleneglycol/succinic acid and 2,2-bishydroxymethylpropane/adipic acid.

The formation of polyesters capped at both ends with hydroxyl groupsshould be minimized. This can be done by controlling the stoichiometryof the reaction so that the acid number and the hydroxyl number of thepolyester are approximately equal.

(4) Polymerization of epoxides with cyclic acid anhydrides in thepresence of excess epoxides.

These reactions, as well as others, are described in greater detail inPreparative Methods of Polymer Chemistry Sorenson and Campbell,Interscience Publishers, Inc., New York, NY. (1961), pp. 111-127 and242-247 and Polyesters and Their Applications, Bjorksten ResearchLaboratories, Inc. Reinhold Publishing Corp., New York, NY. (1956).

(B) Preparation of the polyethylenimine segment Some of thepolyethylenimines are available commercially and can be used directly,without processing. Those polyethylenimines which cannot be obtainedcommercially can be prepared according to the general equation Thepolymers of the invention are made by coupling together the previouslyprepared polyester and polyethylenimine. If the terminal functionalgroup on the polyester can react directly with the polyethylenimine,they can be coupled together by simply mixing stoichiometric amounts ofeach in a vessel and then heating them at a temperature of C. to 120 C.for from A: to 4 hours.

If the functional group on the polyester cannot react directly with thepolyethylenimine, either may be modified by reacting it with astoichiometric amount of an appropriate difunctional compound so that itwill react. Preferably the polyester is so modified.

Illustrative of such a reaction (which will introduce a -Z,,-- linkingradical into the final molecule) are on ooN-orn 0 13-0 b-NH-Q-Cm 1 1EC-A B-OH mom-on-on,

4 O NaiCOl BC CICHaC CH1 ---s In these equations, A signifies thepolyethylenimine segment and B signifies the polyester segment.

After one of the precursors has been reacted with the linking compound,the product and the other precursor are dissolved in a mutual solventsuch as toluene and refluxed for from 1 to 8 hours.

These polymers can be isolated from the reaction mass by adding anon-solvent such as methanol. The resulting precipitate is then filteredoft" and purified by redissolving and precipitating it several times,and then drying it at 60l00 C. in an inert atmosphere.

Ordinarily, the particle dispersant will be present in the followingamounts based on the total weight of the polyester-urethane: generally,about 0.5%25%, preferably, about 3-15% and most preferably, about 510%.

The blend of polyester-urethane, cross-linker, magnetic and/ orconductive particles, organic liquid solvent, and if desired particledispersant can be applied to a suitable support by any suitable method,such as by dipping, brushing, spraying, doctor-blading and the like.Afterwards, it is cured, preferably by the application of heat for ashort period of time. Such compositions can contain about 05-60% polymersolids and preferably, about 15-45% polymer solids. Often the filmproduced by ouring such compositions on a suitable support will have athickness of about 0.1l.5 mils, preferably about 0.5 mil.

Suitable supports may be in the form of a tape, bell, disk or the like.The support can be made from any suitable material including polyesters,such as polyethylene terephthalate, polyvinyl chloride, celluloseacetate, metal, such as copper, brass, aluminum, tin, and the like.Preferred is polyethylene terephthalate, especially that which has beenbiaxially symmetrically or asymmetrically stretched. Especiallypreferred is the polyethylene terephthalate described in U.S. Pat. No.3,397,072, the disclosure of which is hereby incorporated by reference.

The following examples illustrate the invention; all parts andpercentages are by weight unless otherwise specified.

EXAMPLE 1 783.3 grams of terephthalic acid, 403.5 grams of isophthalicacid, 1358.7 grams of azelaic acid and 1241.4 grams of ethylene glycolwere loaded into a 5 liter three neck flask equipped with a packeddistillation column, heating means and agitation means. This mixture washeated at atmospheric pressure to 225 C. taking off the water ofreaction and minor amounts of ethylene glycol.

At 225 C. the packed distillation column was removed, the fiask wasequipped with a condenser, a receiver, an ice trap and a vacuum pump.The heating was continued to 240 C. and the pressure was graduallyreduced to 25 millimeters Hg absolute. These conditions were held untilthe hydroxyl terminated copolyester had a hydroxyl number of 50.4through removal of ethylene glycol; the molecular weight of thecopolyester, calculated from the hydroxyl number, was about 2226. Anacid number of less than 2.0 was attained showing the esterificationreaction was essentially completed.

The heat was turned off and the hydroxyl terminated copolyester wascooled to room temperature. 600 grams of the hydroxyl terminatedcopolyester were loaded into a 2 liter 3 neck flask. 423.9 grams ofmethyl isobutyl ketone were added and a condenser and water separatorfilled with methyl isobutyl ketone were placed in the flask. Heat andagitation were applied until reflux of 122 C. was reached. The batch washeld at reflux to remove any water present for 30 minutes at which timethe heat was turned off.

The water separator was removed and replaced by a straight tube allowingthe refluxing solvent to flow directly back into the flask. At thispoint 37.6 grams of Hylene TM (a mixture of 2,4-toluene diisocyanate and20% toluene 2,6-diisocyanate available from E. I. du Pont de Nemours andCompany) and 1.2 grams of trimethylpyridine catalyst were added insequence. The molar ratio of isocyanate to hydroxyl was about 0.8/ 1.0.

The heat was applied again and reflux attained. The reaction was heldfor 4 hours and then the heat was removed. The resultingpolyester-urethane had a hydroxyl number of 15.9 and a molecular weight(calculated from the hydroxyl number) of about 7057.

The resulting polyester-urethane solution was thinned to 40% solids byadding 531.3 grams of methyl ethyl ketone. 100 parts of thepolyester-urethane solution were admixed with 7.5 parts of across-linker solution (a solution in methyl isobutyl ketone having 60%solids of adduct of 5 moles of a mixture of 80% 2,4-toluene diisocyanateand 20% 2,6-toluene diisocyanate with 2 moles of trimetholpropane, theadduct having a functionality of 4 NCO groups per molecule).

The resulting admixture was applied to a film of Mylar polyester film bydrawdown with a wire wound rod, the solvent removed and laminated toanother Mylar polyester film using a Sentinel heat sealer. The Mylarpolyester films were found to have excellent adhesion to each other.

EXAMPLE 2 A polyester-urethane was produced using the procedure ofExample 1. 1304.00 grams of phthalic anhydride, 1286.38 grams of adipicacid and 1215.01 grams of ethylene glycol were reacted to produce ahydroxyl terminated copolyester having a hydroxyl number of 49.7 and amolecular weight (calculated from the hydroxyl number) of about 2258.

928.1 grams of the hydroxyl terminated copolyester were admixed with270.9 grams of methyl isobutyl ketone. This mixture was dried and 24.7grams of additional methyl isobutyl ketone was removed to assureanhydrous conditions. To this mixture 0.6 gram of N-ethyl morpholine and58.9 grams of Hylene TM mixture of 2,4- and 2,6-toluene diisocyanatewere admixed and reacted. The molar ratio of isocyanate to hydroxyl wasabout 0.8/1.0. The resulting polyester-urethane had a hydroxyl number of14.2 and a molecular weight (calculated from the hydroxyl number) ofabout 7901.

The polyester-urethane was reduced to 60% solids by adding 411.2 gramsmethyl ethyl ketone. 100 parts of the polyester-urethane solution wereadmixed with 14.4 parts of the cross-linker solution described inExample 1. Then, the resulting admixture was tested for adhesion as inExample 1. Excellent results were obtained.

EXAMPLE 3 A polyester-urethane was produced using the procedure ofExample 1. 872 grams terephthalic acid, 816.6 grams azelaic acid and740.2 grams ethylene glycol were reacted to produce a hydroxylterminated copolyester having a hydroxyl number of 36.2 and a molecularweight (calculated from the hydroxyl number) of about 3099.

The hydroxyl terminated copolyester was reduced to 60% solids by theaddition of 1,1,2-trichloroethane.

500 grams of the reduced solution of hydroxyl terminated copolyesterwere dried as in Example 1. To the dried solution, 0.6 gramtrimethylpyridine and 16.0 grams Hylene TM mixture of 2,4- and2,6-toluene diisocyanate were added followed by application of heat toproduce reflux for 3 hours to produce a polyester-urethane. The molarratio of isocyanate to hydroxyl was about 0.95 1.0. Thepolyester-urethane had a hydroxyl number of 6.4 and a molecular weight(calculated from the hydroxyl number) of about 17,531.

The polyester-urethane solution was reduced to 15% solids by adding1316.7 grams of 1,1,2-trichloroethane. 100 parts of thepolyester-urethane solution were admixed with 2.6 parts of thecross-linker solution described in Example 1. Then, the resultingadmixture was tested for adhesion as in Example 1. Excellent resultswere obtained.

12 EXAMPLE 4 A polyester-urethane was produced using the procedure ofExample 1. 1006.7 grams terephthalic acid, 1006.7 grams isophthalicacid, 288.1 grams azelaic acid, 221.4 grams adipic acid and 1175.1 gramsethylene glycol were reacted to produce a hydroxyl terminatedcopolyester having a hydroxyl number of 65.5 and a molecular weight(calculated from the hydroxyl number) of about 1713.

150 grams of the hydroxyl terminated copolyester were mixed with 120grams toluol, dried removing 10 grams toluol and reacted for 45 minuteswith 15.2 grams Hylene TM mixture of 2,4- and 2,6-toluene diisocyanateusing 0.3 gram trimethylpyridene catalyst. The molar ratio of isocyanateto hydroxyl was about 1.0/1.0. The resulting polyester-urethane had ahydroxy number of 6.1 and a molecular weight (calculated from thehydroxyl number) of about 18,393.

The polyester-urethane solution was thinned to 20% solids with 456.9grams methyl ethyl ketone and 86.5 grams toluol. parts of thepolyester-urethane solution were admixed with 3.25 parts of thecross-linker solution described in Example 1. Then, the resultingadmixture was tested for adhesion as in Example 1. Excellent resultswere obtained.

EXAMPLE 5 A polyester-urethane was produced using the procedure ofExample 1. 826.8 grams terephthalic acid, 330.9 grams isophthalic acid,567.9 grams azelaic acid, 980.1 grams polytetramethylene ether glycoland 772.2 grams ethylene glycol were reacted to produce a hydroxylterminated copolyester having a hydroxyl number of 54.5 and a molecularweight (calculated from the hydroxyl number) of about 2059'.

600.0 grams of the hydroxyl terminated copolyester were reduced with520.4 grams toluol, dried removing 86.8 grams of toluol and reacted for2 hours with 50.8 grams Hylene TM mixture of 2,4- and 2,6-toluenediisocyanate using 1.2 grams trimethylpyridene catalyst. The molar ratioof isocyanate to hydroxyl was about 1.0/ 1.0. The resultingpolyester-urethane had a hydroxyl number of 11.2 and a molecular weight(calculated from the hydroxyl number) of about 10,018.

The polyester-urethane solution was thinned to 40% solids with 544.0grams methyl ethyl ketone. 100 parts of the polyester-urethane solutionwere admixed with 4.25 parts of the cross-linker solution described inExample 1. Then, the resulting admixture was tested for adhesion as inExample 1. Excellent results were obtained.

EXAMPLE 6 A polyester-urethane was produced using the procedure ofExample 1. 592 grams phthalic anhydride, 632 grams C -C mixed aliphaticdicarboxylic acid and 620 grams ethylene glycol were reacted to producea hydroxyl terminated copolyester having a hydroxyl number of 25.3 and amolecular weight (calculated from the hydroxyl number) of about 4435.

465.7 grams of the hydroxyl terminated copolyester were mixed and driedwith 146.7 grams of methyl isobutyl ketone removing 12.1 grams of themethyl isobutyl ketone. This solution of copolyester was reacted with14.4 grams of Hylene TM mixture of 2,4- and 2,6-toluene diisocyanate for4 hours using 0.14 gram of N-ethyl morpholine. The molar ratio ofisocyanate to hydroxyl was about 08/10. The resulting polyesterurethanehad a hydroxyl number of 7.6 and a molecular weight (calculated from thehydroxyl number) of about 14,763.

The polyester-urethane solution was thinner to 60% solids with 185.36grams methyl ethyl ketone. 100 parts of the polyester-urethane solutionwere admixed with 12.6 parts of the cross-linker solution described inExample 1. Then, the resulting admixture was tested for adhesion as inExample 1. Excellent results were obtained.

13 EXAMPLE 7 A polyester-urethane was produced using the procedure ofExample 1. 289.4 grams terephthalic acid, 1290.6 grams phthalicanhydride, 1018.4 grams adipic acid and 1357.7 grams ethylene glycolwere reacted to produce a hydroxyl terminated copolyester having ahydroxyl number of 33.2 and a molecular weight (calculated from thehydroxyl number) of about 3380.

900 grams of the hydroxyl terminated copolyester and 257.04 grams ofmethyl isobutyl ketone were mixed followed by drying to remove 23.4grams methyl isobutyl ketone in the process.

The dried solution of the copolyester was reacted with 36.9 grams HyleneTM mixture of 2,4- and 2,6-toluene diisocyanate for 4 hours using 0.36grams triethylamine as the catalyst. The molar ratio of isocyanate tohydroxyl was about 0.8/1.0. The resulting polyester-urethane had ahydroxyl number of 9.0 and a molecular weight (calculated from thehydroxyl number) of about 12,467.

The polyester-urethane solution was thinner to 60% solids with 390.6grams methyl ethyl ketone. 100 parts of the polyester-urethane solutionwere admixed with parts of the cross-linker solution described inExample 1. Then, the resulting admixture was tested for adhesion as inExample 1. Excellent results were obtained.

EXAMPLE 8 The polyester-urethanes with cross-linkers of Examples 1-7 canbe reduced to suitable solids, pigmented, if desired, and admixed withdispersing agents as required to produce coating compositions. Thesecoating compositions can be used to coat suitable substrates.

EXAMPLE 9 (A) Prepration of particle dispersant A solution of 200 partsof polycaprolactone (molecular weight 3000) in 465 parts of benzene wasadded dropwise over a two hour period to a refluxing solution of 11.6parts of 2,4-toluenediisocyanate and 0.13 part dibutyl tin dilaurate in100 parts of benzene.

The solution was refluxed for 30 minutes, cooled and 388 parts wereadded to 10 parts of triethylene tetramine (molecular weight 600) in 50parts of dimethylformamide.

The mixture was stirred for 1 hour at room temperature and thenprecipitated in methanol. The polymer was filtered off and dried in avacuum at 60 C. Its structure was (B) Preparation of bindercomposition 1) A solution was prepared of 24 parts of the hydroxylterminated polyester-urethane of Example 1 and 2.5 parts of the particledispersant above-described in (A) in 88.5 parts of a 70/ 10/5cyclohexanone, methylethyl ketone, methylisobutyl ketone, toluenemixture.

(2) A thin slurry of 66 parts of iron oxide (magnetic tape grade) and 4parts of conductive carbon in a small amount of the solution in (l) wasball-milled for 24 hours.

(3) The remainder of the solution in (1) was then added to the slurry in-(1). The mixture was ball-milled for 2 hours. To this were then added,with mixing, 3 parts of the cross-linker described in Example 1 and 0.5part of butyl stearate.

The resulting binder composition was doctor-bladed on a sheet of Mylarpolyester film to a thickness of 0.5 mil (dry) and then baked for oneminute at 100 C.

14 The sheet was then cut into M: inch strips.

This magnetic tape showed good adhesion of the coating to the substrateand had good electrical properties.

The invention claimed is:

1. A cross-linked polyester urethane produced by (A) admixing at leastone linear copolyester, such copolyester (1) produced by the reaction ofone or more diols or polyether glycols with at least two differentdicarboxylic acids, anhydrides of dicarboxylic acids, or methyl estersof dicarboxylic acids, about 40-80 mole percent of said dicarboxylicacids, anhydrides of dicarboxylic acids or methyl esters of dicarboxylicacids being aromatic and about -20 mole percent of said dicarboxylicacids, anhydrides of dicarboxylic acids or methyl esters of dicarboxylicacids being aliphatic, said aromatic component being selected from thegroup consisting essentially of terephthalic acid, isophthalic acid,orthophthalic acid, phthalic anhydride and mixtures thereof and saidaliphatic components being selected from the group consisting ofsuccinic acid, glutaric acid, azelaic acid, sebacic acid and mixturesthereof, (2) having a hydroxyl number of about 20-225 (3) having amolecular weight of about 500- about 10,000 (4) having about twohydroxyl groups per molecule with (B) at least one organic diisocyanate,the molar ratio of isocyanate contained on the diisocyanate to hydroxylcontained on the copolyester being sufficient for the conditions of thereaction temperature and reaction time to form a polyester-urethanehaving about two hydroxyl groups per molecule, and

(C) admixing the polyester-urethane with at least one cross-linker, suchcross-linker containing groups that are reactive with the hydroxylgroups carried by the polyester-urethane of (B) and having afunctionality greater than 2, the molar ratio of groups contained on thecross-linker to hydroxyls contained on the polyester-urethane beingabout 1.0/1.0 to 4.0/1.0 at a temperature and for a time suflicient toproduce the cross-linked polyester-urethane.

2. The cross-linked polyester-urethane of claim 1 wherein thefunctionality of the cross-linker is greater than about 2 and no greaterthan about 8.

3. The cross-linked polyester-urethane of claim 1 wherein thefunctionality of the cross-linker is about 3-6.

4. The cross-linked polyester-urethane of claim 1 wherein thefunctionality of the cross-linker is about 4-6.

5. The cross-linked polyester-urethane of claim 1 wherein thefunctionality of the cross-linker is about 4.

6. The cross-linked polyester-urethane of claim 1 wherein thecross-linker is an adduct of toluene-2,4-diisocyanate, toluene 2,6diisocyanate or mixtures thereof with trimethylolpropane in a 5:2 moleratio, such crosslinker having a functionality of about 4.

7. The cross-linked polyester-urethane of claim 1 wherein the molarratio of isocyanate contained on the diisocyanate to hydroxyl containedon the copolyester is about 0.7/1.0 to about 1.0/1.0.

8. The cross-linked polyester-urethane of claim 1 wherein the molarratio of isocyanate contained on the diisocyanate to hydroxyl containedon the copolyester is about 0.7/ 1.0 to about 0.98/10.

9. The cross-linked polyester-urethane of claim 1 wherein the molarratio of isocyanate contained on the diisocyanate to hydroxyl containedon the copolyester is about 0.75/1.0 to about 0.9/1.0.

10. The cross-linked polyester-urethane of claim 1 wherein the molarratio of isocyanate contained on the diisocyanate to hydroxyl containedon the copolyester is about 0.80/1.0 to about 0.85/10.

11. The cross-linked polyester-urethane of claim 1 wherein the organicdiisocyanate is a mixture of toluene- 2,4-diisocyanate andtoluene-2,6-diisocyanate.

12. The cross-linked polyester-urethane of claim 1 wherein thecopolyester has a hydroxyl number of about 40 to about 225 and amolecular weight of about 1800 to about 10,000.

13. The cross-linked polyester-urethane of claim 1' wherein thecopolyester has a hydroxyl number of about 40 to about 60 and amolecular weight of about 1800 to about 2800.

14. The cross-linked polyester-urethane of claim 1 wherein saidcopolyester is produced from the reaction of ethylene glycol,polytetramethylene ether glycol or mixtures thereof with at least twoditferent dicarboxylic acids or anhydrides of dicarboxylic acid selectedfrom the group consisting of terephthalic acid, isophthalic acid,orthophthalic acid, phthalic anhydride, azelaic acid, adipic acid andmixtures of C aliphatic dicarboxylic acid.

15. The cross-linked polyester-urethane of claim 1 wherein thecopolyester is produced from acid mixtures selected from the followinggroups (A)-(G):

(A) terephthalic acid 28-38 mole percent, isophthalic acid 12-22 molepercent and azelaic acid 40-60 mole percent,

(B) orthophthalic acid or phthalic anhydride 40-60 mole percent andadipic acid 40-60 mole percent,

(C) terephthalic acid 45-65 mole percent and azelaic acid 33-55 molepercent,

(D) terephthalic acid 35-45 mole percent, isophthalic acid 35-45 molepercent, azelaic acid -15 mole percent and adipic acid 5-15 molepercent,

(E) terephthalic acid 45-55 mole percent, isophthalic acid -25 molepercent, and azelaic acid -40 mole percent,

(F) orthophthalic acid or phthalic anhydride 40-60 mole percent andmixtures of C -C aliphatic dicarboxylic acids 40-60 mole percent, and

(G) terephthalic acid 5-15, orthophthalic acid or phthalic anhydride40-60 mole percent and adipic acid -55 mole percent.

16. The cross-linked polyester-urethane of claim 1 wherein thecopolyester is produced from acid mixtures selected from the followinggroups (A)-(G):

(A) terephthalic acid 33 mole percent, isophthalic acid 17 mole percent,and azelaic acid 50 mole percent,

(B) orthophthalic acid or phthalic anhydride 50 mole percent and adipicacid 50 mole percent,

(C) terephthalic acid 55 mole percent and azelaic acid 45 mole percent,

(D) terephthalic acid 40 mole percent, isophthalic acid 40 mole percent,azelaic acid 10 mole percent and adipic acid 10 mole percent,

(E) terephthalic acid 50 mole percent, isophthalic acid 20 mole percentand azelaic acid mole percent,

(F) orthophthalic acid or phthalic anhydride 50 mole percent, andmixtures of C -C aliphatic dicarboxylic acids 50 mole percent,

(G) terephthalic acid 10 mole percent, orthophthalic acid or phthalicanhydride 50 mole percent and adipic acid mole percent.

17. The cross-linked polyester-urethane of claim 15 wherein thecopolyester is produced from ethylene glycol, polytetramethylene etherglycol or mixtures thereof.

18. The cross-linked polyester-urethane of claim 1 wherein thecross-linker is an adduct of toluene-2,4-diisocyanate, toluene 2,6diisocyanate or mixtures thereof with trimethylol propane in a 5:2 molarratio, such crosslinker having a functionality of about 4,

the molar ratio of isocyanate to hydroxyl being about 0.80/1.0 to about0.85/1.0, and

the organic diisocyanate being a mixture of toluene-2,4-

diisocyanate and toluene-2,6-diisocyanate.

19. The cross-linked polyester-urethane of claim 18 wherein thecopolyester has a hydroxyl number of about 40 to about 60, and amolecular weight of about 1800 to about 2800, and

the copolyester is produced from the reaction of ethylene glycol,polytetramethylene ether glycol or mixtures thereof with at least twodifferent dicarboxylic acids or anhydrides of dicarboxylic acidsselected from the groups consisting of terephthalic acid, isophthalicacid, orthophthalic acid, phthalic anhydride, azelaic acid, adipic acidand mixtures of C C aliphatic dicarboxylic acid.

20. The cross-linked polyester-urethane of claim 19 wherein thecopolyester is produced from the reaction of acid mixtures selected fromthe following groups (A)- (G):

(A) terephthalic acid 28-38 mole percent, isophthalic acid 12-22 molepercent and azelaic acid 40-60 mole percent,

(B) orthophthalic acid or phthalic anhydride 40-60 mole percent andadipic acid 40-60 mole percent,

(C) terephthalic acid 45-65 mole percent and azelaic acid 33-55 molepercent,

(D) tetephthalic acid 35-45 mole percent, isophthalic acid 35-45 molepercent, azelaic acid 5-15 mole percent and adipic acid 5-15 molepercent,

(E) terephthalic acid 45-55 mole percent, isophthalic acid 15-25 molepercent, and azelaic acid 20-40 mole percent,

(F) orthophthalic acid or phthalic anhydride 40-60 mole percent andmixtures of C -C aliphatic dicarboxylic acids 40-60 mole percent, and

(G) terephthalic acid 5-15, orthophthalic acid or phthalic anhydride40-60 mole percent and adipic acid 25-55 mole percent.

21. The cross-linked polyester-urethane of claim 19 wherein thecopolyester is produced from the reaction of acid mixtures selected fromthe following groups (A)- (G):

(A) terephthalic acid 33 mole percent, isophthalic acid 17 mole percent,and azelaic acid 50 mole percent,

(B) orthophthalic acid or phthalic anhydride 50 mole percent and adipicacid 50 mole percent,

(C) terephthalic acid 55 mole percent and azelaic acid 45 mole percent,

(D) terephthalic acid 40 mole percent, isophthalic acid 40 mole percent,azelaic acid 10 mole percent and adipic acid 10 mole percent,

(E) terephthalic acid 50 mole percent, isophthalic acid 20 mole percentand azelaic acid 30 mole percent,

(F) orthophthalic acid or phthalic anhydride 50 mole percent, andmixtures of C -C aliphatic dicarboxylic acids 50 mole percent,

(G) terephthalic acid 10 mole percent, orthophthalic acid or phthalicanhydride 50 mole percent and adipic acid 40 mole percent.

22. The cross-linked polyester-urethane of claim 19 wherein thecopolyester is produced from ethylene glycol.

23. The cross-linked polyester-urethane of claim 1 contained in organicliquid solvent.

24. The composition of claim 23 containing about 05-25% by weight, basedon the weight of the polyester-.

R R and R are hydrogen, alkyl radicals of 1 through 4 carbon atoms, CHCH NH or CH CH OH; R is hydrogen or an alkyl radical of 1 through 4carbon atoms;

Z is an organic linking radical;

B is

O x t] o.,

0 o o-sr-o-ii-x-iil on 0 O O 182804-011-.. where the n/ a quotient beinggreater than 1.

26. The composition of claim 25 wherein the particle dispersant has theformula:

27. The composition of claim 25 containing about 6.5- 80% by weightbased on the total weight of the polyesterurethane of magnetic and/ orconductive particles.

28. Article comprising a support and adhered to the support of a layerof cross-linked polyester-urethane, said cross-linked polyester-urethanecontaining about 05-25% by weight based on the weight of thepolyester-urethane of the particle dispersant described in claim 25 andabout -80% by weight based on the weight of the polyesterurethane ofmagnetic and/or conductive particles.

29. Composition of claim 23 containing pigment.

References Cited UNITED STATES PATENTS 3,008,917 11/1961 Park et a126045.4 3,202,728 8/1965 Kohn 260-858 3,238,056 3/1966 Pall et al.117-98 3,255,069 6/1966 Crowley et a1. 161-190 3,384,506 5/1968 Elkin117-62 3,490,987 1/1970 Bauriedel 161-190 2,929,800 3/ 1960 Hill260-77.5 3,079,350 2/1963 Bernstein 260-2.5 3,170,833 2/1965 Noyes161-186 3,341,498 9/1967 Skreckoski et a1. 260- 3,365,526 1/ 1968 Wiedenet a1. 264-176 3,428,609 2/ 1969 Chilvers et a1. 260-75 3,554,951 1/1971Blomeyer et a1 260-29.1 3,574,684 4/1971 Higashi 117-237 DONALD E. CZAJA, Primary Examiner H. S. COCKERAM, Assistant Examiner US. Cl. X.R.

117-161; 161-190; 260-'30.4 N, 31.2 N, 31.4 R, 31.8 R, 32.8 N, 33.2 R,33.6 UB, 33.8 UB, 37 N, 77.5 SS, 858

